System and method for uplink timing synchronization in conjunction with discontinous reception

ABSTRACT

Systems and methods for controlling sounding reference signal transmission are provided; a user equipment starts transmitting the sounding reference signal in anticipation of uplink data transmission, and then discontinues transmitting the sounding reference signal after completion of uplink data transmission.

BACKGROUND

In traditional wireless telecommunications systems, transmissionequipment in a base station transmits signals throughout a geographicalregion known as a cell. As technology has evolved, more advanced networkaccess equipment has been introduced that can provide services that werenot possible previously. This advanced network access equipment mightinclude, for example, an enhanced node-B (eNB) rather than a basestation or other systems and devices that are more highly evolved thanthe equivalent equipment in a traditional wireless telecommunicationssystem. Such advanced or next generation equipment is typically referredto as long-term evolution (LTE) equipment. For LTE equipment, the regionin which a wireless device can gain access to a telecommunicationsnetwork might be referred to by a name other than “cell”, such as “hotspot”. As used herein, the term “cell” will be used to refer to anyregion in which a wireless device can gain access to atelecommunications network, regardless of whether the wireless device isa traditional cellular device, an LTE device, or some other device.

Devices that might be used by users in a telecommunications network caninclude both mobile terminals, such as mobile telephones, personaldigital assistants, handheld computers, portable computers, laptopcomputers, tablet computers and similar devices, and fixed terminalssuch as residential gateways, televisions, set-top boxes and the like.Such devices will be referred to herein as user equipment or UE.

In wireless communication systems, transmission from the network accessequipment (e.g., eNB) to the UE is referred to as a downlinktransmission. Communication from the UE to the network access equipmentis referred to as an uplink transmission. Wireless communication systemsgenerally require maintenance of timing synchronization to allow forcontinued communications. Maintaining uplink synchronization can beproblematic, wasting throughput and/or decreasing battery life of a UEgiven that a UE may not always have data to transmit.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of this disclosure, reference is nowmade to the following brief description, taken in connection with theaccompanying drawings and detailed description, wherein like referencenumerals represent like parts.

FIG. 1 is an illustration of a cellular network according to anembodiment of the disclosure;

FIG. 2 is an illustration of a cell in a cellular network according toan embodiment of the disclosure;

FIG. 3 is an illustration of a possible uplink transmission channel;

FIG. 4 is a timing diagram;

FIG. 5 is a flowchart showing an example of a method of uplink referencesignal transmission;

FIG. 6 is a timing diagram showing an example of uplink reference signaltiming;

FIG. 7 is a flowchart of a method of uplink reference signaltransmission by a UE;

FIG. 8 is a flow chart of a method in network access equipment thatcorresponds with the method of FIG. 7;

FIG. 9 is an exemplary diagram of modules in the UE.

FIG. 10 is a diagram of a wireless communications system including amobile device operable for some of the various embodiments of thedisclosure;

FIG. 11 is a block diagram of a mobile device operable for some of thevarious embodiments of the disclosure;

FIG. 12 is a diagram of a software environment that may be implementedon a mobile device operable for some of the various embodiments of thedisclosure; and

FIG. 13 is an exemplary general purpose computer according to oneembodiment of the present disclosure;

DETAILED DESCRIPTION

According to one broad aspect, the application provides a method ofuplink reference signal transmission in a user equipment comprising:starting uplink reference signal transmission in anticipation oftransmitting uplink data; transmitting uplink data after starting uplinkreference signal transmission; continuing uplink reference signaltransmission until completion of transmission of the uplink data.

According to another broad aspect, the application provides a computerreadable medium having computer executable instructions stored thereonfor implementing a method comprising: starting uplink reference signaltransmission in anticipation of transmitting uplink data; transmittinguplink data after starting uplink reference signal transmission;continuing uplink reference signal transmission until completion oftransmission of the uplink data.

According to another broad aspect, the application provides a userequipment comprising: a receive module; an uplink signal generationmodule that starts generating the uplink reference signal inanticipation of transmitting uplink data and continues to generateuplink reference signals until completion of transmission of the uplinkdata; and a transmit module configured to transmit the uplink data andto transmit the uplink reference signals generated by the uplink signalgeneration module.

It should be understood at the outset that although illustrativeimplementations of one or more embodiments of the present disclosure areprovided below, the disclosed systems and/or methods may be implementedusing any number of techniques, whether currently known or in existence.The disclosure should in no way be limited to the illustrativeimplementations, drawings, and techniques illustrated below, includingthe exemplary designs and implementations illustrated and describedherein, but may be modified within the scope of the appended claimsalong with their full scope of equivalents.

FIG. 1 illustrates an exemplary cellular network 100 according to anembodiment of the disclosure. The cellular network 100 may include aplurality of cells 102 ₁, 102 ₂, 102 ₃, 102 ₄, 102 ₅, 102 ₆, 102 ₇, 102₈, 102 ₉, 102 ₉, 102 ₁₀, 102 ₁₁, 102 ₁₂, 102 ₁₃, and 102 ₁₄(collectively referred to as cells 102). As is apparent to persons ofordinary skill in the art, each of the cells 102 represents a coveragearea for providing cellular services of the cellular network 100 throughcommunication from a network access equipment (e.g., eNB). While thecells 102 are depicted as having non-overlapping coverage areas, personsof ordinary skill in the art will recognize that one or more of thecells 102 may have partially overlapping coverage with adjacent cells.In addition, while a particular number of the cells 102 are depicted,persons of ordinary skill in the art will recognize that a larger orsmaller number of the cells 102 may be included in the cellular network100.

One or more UEs 10 may be present in each of the cells 102. Althoughonly one UE 10 is depicted and is shown in only one cell 102 ₁₂, it willbe apparent to one of skill in the art that a plurality of UEs 10 may bepresent in each of the cells 102. A network access equipment 20 in eachof the cells 102 performs functions similar to those of a traditionalbase station. That is, the network access equipments 20 provide a radiolink between the UEs 10 and other components in a telecommunicationsnetwork. While the network access equipment 20 is shown only in cell 102₁₂, it should be understood that network access equipment would bepresent in each of the cells 102.

FIG. 2 depicts a more detailed view of the cell 102 ₁₂. The networkaccess equipment 20 in cell 102 ₁₂ may promote communication via atransmitter 27, a receiver 29, and/or other well known equipment.Similar equipment might be present in the other cells 102. A pluralityof UEs 10 are present in the cell 102 ₁₂, as might be the case in theother cells 102. In the present disclosure, the cellular systems orcells 102 are described as engaged in certain activities, such astransmitting signals; however, as will be readily apparent to oneskilled in the art, these activities would in fact be conducted bycomponents comprising the cells.

In each cell, the transmissions from the network access equipment 20 tothe UEs 10 are referred to as downlink transmissions, and thetransmissions from the UEs 10 to the network access equipment 20 arereferred to as uplink transmissions. The UE may include any device thatmay communicate using the cellular network 100. For example, the UE mayinclude devices such as a cellular telephone, a laptop computer, anavigation system, or any other devices known to persons of ordinaryskill in the art that may communicate using the cellular network 100.

The format of an example of an uplink channel is shown schematically inFIG. 3. The transmission can be one of a number of different bandwidths(e.g., 1.25, 5, 15, or 20 MHz). In the time domain, the uplink is brokeninto frames, sub-frames and slots. Each slot 201 (shown as slots 201 ₁,201 ₂, . . . , 201 ₁₉, 201 ₂₀, collectively slots 201) is made up ofseven orthogonal frequency division multiplexed (OFDM) symbols 203. Twoslots 201 make up a sub-frame 205 (sub-frames 205 ₁, 205 ₂, . . . , 205₁₀, collectively are sub-frames 205). A frame is a collection of 10contiguous sub-frames. Because the exact details of a sub-frame 205 mayvery depending upon the exact implementation, the following descriptionis provided as an example only. The UE will transmit using aconstant-amplitude and zero-autocorrelation (CAZAC) sequence so thatmore than one UE may transmit simultaneously. The demodulation (DM)reference symbol (RS) is placed on the fourth symbol 209 of each slot;and the control channel 211 is taken up by at least one resource blockon the very outside edges of the frequency band.

Uplink reference signal transmission opportunities for channel qualityassessment and/or timing alignment (e.g. SRS (sounding referencesignal)) transmission opportunities may exist anywhere in each sub-frame205 and most likely at the beginning, or end. Each such transmissionopportunity is broken down into several blocks of 12 sub-carriers thatcorrespond to the same frequency bandwidth as a resource block. A UE mayuse one or all of those frequency blocks depending on the transmissionbandwidth selected. The UE may also use every other sub-carrier in oneor more multiple blocks. In the illustrated example, an SRS is shown inthe first symbol 207 of the sub-frame 205 ₁ and of sub-frame 201 ₁₉.FIG. 3 also shows where in time and frequency that the physical uplinkcontrol channel (PUCCH) 211 is placed. Control signaling takes place inthe PUCCH. In one embodiment, the system implements a hybrid automaticrepeat request (HARQ) acknowledgement (ACK)/negative acknowledgement(NACK) feedback. An ACK or NACK is sent on the PUCCH 211 by the UE tothe eNB to indicate whether a packet transmitted from the eNB wasreceived at that UE. The physical uplink shared channel (PUSCH) is usedto send user data.

The above description of the uplink channel is one implementation of anuplink channel. It will be appreciated that other uplink channelconfigurations may be used wherein an uplink reference signaltransmission (e.g., SRS) is sent during any portion of the uplinkmessage, not necessarily only at the beginning or end of a specifiedtime interval (e.g., slot).

In order to maintain uplink synchronization, it is desirable for thenetwork access equipment 20 (shown in FIG. 1) to calculate the uplinkchannel conditions by analyzing signals sent from the UE 10. Onepossible timing diagram of signals sent between the network accessequipment 20 and the UE 10 is shown in FIG. 4. In this embodiment, thenetwork access equipment 20 instructs the UE 10 when to send an uplinkreference signal transmission (e.g., SRS), through use of an uplinkreference signal transmission instruction message 241. The uplinkreference signal transmission instruction message 241 may include anyone of a variety of instructions. For example, the network accessequipment 20 may instruct the UE 10 via the reference signaltransmission instruction message 241 to send the reference signaltransmissions at a constant rate, or in bursts depending on the velocityof the UE 10 relative to the network access equipment 20. In response243, the UE 10 may send the reference signal transmissions (e.g., SRS)in accordance with the instructions of the network access equipment 20.

In order to conserve battery power in the UE, the UE may operate withdiscontinuous reception (DRX). Typically, the UE will turn its receptioncapability on and off in a repeating fashion. The network is aware ofthe DRX behavior and makes its transmission to the UE during periodsthat the reception capability is on. An On period followed by an Offperiod is a DRX cycle.

DRX in Connected Mode will be configured by the network. Part of theconfiguration is the setting of the DRX-cycle On Duration, inactivitytimers and HARQ timer. During the On periods (periods the receiver is oneach having a length specified by the On Duration), the UE will monitorthe PDCCH (packet data control channel) or configured resource for theallocation of possible downlink and uplink transmissions. When a PDCCHis decoded successfully, an inactivity timer will be started. At the endof the On period, the UE may go back to sleep according to the DRXconfiguration.

Transmission of Uplink Reference Signal in Anticipation of UplinkTransmission

In some embodiments, the UE does not transmit an uplink reference signaluntil it determines that it has uplink data to send. Upon making such adetermination, the UE transmits the uplink reference signal inanticipation of the uplink transmission, for example slightly before thestart of the uplink transmission, and during the uplink transmission.The UE then stops transmitting the uplink reference signal aftercompletion of the uplink transmission. A flowchart of the method will bedescribed with reference to FIG. 5. The method begins with controlling areceiver in the user equipment to have on periods and off periods atblock 5-1. Note that these on and off periods may for the most part beperiodic or for the most part periodic in some embodiments, but moregenerally they need not be necessarily periodic. The method continues inblock 5-2 with starting uplink reference signal transmission inanticipation of transmitting uplink data. The method continues at block5-3 with the user equipment transmitting uplink data after havingstarted uplink reference signal transmission. At block 5-4, the userequipment continues uplink reference signal transmission untilcompletion of transmission of the uplink data.

The embodiment of FIG. 5 assumes that the uplink reference signaltransmission in anticipation of uplink data transmission is in thecontext of DRX control of the receiver. In another embodiment, blocks5-2,5-3,5-4 are executed by a user equipment that is not operating inDRX mode in which case block 5-1 can be omitted.

Referring now to FIG. 6, a specific example will be described. In thisexample and all of the examples that follow, the reference signals areassumed to be SRS transmissions. It is to be understood that all of theexamples given have application more generally to reference signals.FIG. 6 shows the timing of various signals for a UE in DRX mode. Shownis DRX timing 800 for a DRX cycle assignment, timing 810 foravailability of data for transmission, timing 822 for uplink datatransmission, a scheduling request timing indicated at 830, and SRStiming indicated at 820. The DRX timing 800 consists of a DRX cycle 802that includes a DRX On Duration (indicated at 804) and a DRX OffDuration. The receiver is alternately turned on for On periods havingthe DRX On Duration and off for Off periods having the DRX Off Duration.The SRS timing 820 has an SRS period 822. This represents the timing ofan uplink resource that is available for SRS transmission. Moregenerally, the UE maintains a definition of an available set of uplinkreference signal transmission opportunities. In some embodiments,information defining these transmission opportunities is contained insignalling information transmitted to the UE by the network. In theillustrated example, the uplink resource is a periodic resource but inother embodiments, the resource is not necessarily periodic. In theillustrated example, there is a ratio of 12 SRS periods to one DRX cycle802 but this is implementation specific. As described below, an SRS isnot transmitted at every opportunity. The timing 810 of the availabilityof data to be sent on the uplink may for example indicate when dataarrives in a buffer for transmission. For the purpose of this example,it is assumed that data is available at 812 for transmission on theuplink. For the specific example indicated, the scheduling requesttiming 830 shows a scheduling request transmitted by the UE at 832 inrespect of the data available at 812. In some embodiments, a schedulingrequest is an indication sent by the UE to the base station to request apreviously assigned uplink resource that may be semi-persistent innature; this means that the same resource is assigned each time the UErequests the resource so that details of the assignment do not need tobe signaled each time. The timing of the resulting uplink datatransmission is indicated at 825. The uplink transmission may forexample occur using a semi-persistent resource. More generally, for theexample of FIG. 6, the SRS behaviour can be in respect of any uplinktransmission; this may involve transmissions using a semi-persistentresource, or dynamically scheduled transmissions to name a few examples.

In the illustrated example, data arrives at 812 for transmission on theuplink between DRX On Durations. Rather than waiting until the next OnDuration to transmit the SR at 832, the UE is allowed to transmit whenit receives data for transmission. In some embodiments, the UE transmitsthe SR (more generally the UE requests an uplink transmission resourceusing some request mechanism) using an assigned scheduling requestchannel assignment at the next available opportunity after the start ofreceipt of data for uplink transmission. In some embodiments, in theevent DRX control has the receiver off when the SR is transmitted, theUE will turn on its receiver in order to receive an uplink grant. Therequest may for example be sent using an uplink resource previouslyassigned for that purpose; it may be a dedicated resource for a given UEor a contention-based resource to name a few examples. This may reduceaverage UL latencies and problems with channel congestion during OnDurations Cycles that may occur when the UE is restricted totransmitting during DRX On Cycle Durations. In such embodiments, therequest for the uplink transmission resource and the subsequenttransmission of the uplink data are both performed irrespective of theon and off periods of the receiver. In some embodiments, the networktransmits signalling to the UE to configure the user equipment to beable to transmit the request for the uplink transmission resource and totransmit the uplink data irrespective of the on and off periods of thereceiver. In other embodiments, the UE is able to behave in this mannerwithout receiving signalling from the network.

SRS transmission is triggered in anticipation of data transmission 825.Specifically, as shown, SRS transmission occurs over a period 824 whichencompasses the timing of the uplink data transmission 825. After dataarrives to be sent by the UE, the SRS is transmitted. The SRStransmission starts before data transmission starts and is discontinuedafter the data has been transmitted. In some embodiments, this involvescontinuing uplink reference signal transmission until a last of theavailable set of uplink reference signal transmission opportunities thatoccur during uplink data transmission and then discontinuing referencesignal transmission as shown for the example of FIG. 6.

In some embodiments, after transmission of an SR (such as at 832), thenetwork responds with an uplink grant on a downlink control channel,such as the PDCCH (packet data control channel) described in TS 36.211(see section 6) hereby incorporated by reference in its entirety. Insome embodiments, an inactivity timer is used to control when todiscontinue SRS transmission. For example, receipt of the uplink grantmay be used as a trigger to start an inactivity timer. The SRStransmission is discontinued after the inactivity timer expires.

SRS Transmission at Closest SRS Transmission Opportunity in the UplinkBefore Uplink Resource Request

In some embodiments, the UE starts making SRS transmissions at theclosest SRS transmission opportunity in the uplink before making anuplink resource request. In such embodiments, the mobile devicemaintains a definition of a set of available SRS transmissionopportunities as described previously. The latest of these opportunitiesthat occurs prior to making an uplink resource request is the one withinwhich the SRS transmission starts. The example of FIG. 6 illustratesthis. It can be seen that SRS transmission opportunity 825 is the latestSRS transmission opportunity that occurs prior to transmitting the SR at832.

In some embodiments, this behaviour is in respect of an uplink resourcerequest for a semi-persistent resource; this may for example involveusing the above described SR mechanism; in some embodiments, thisbehaviour is in respect of an uplink resource request that is atransmitted using a contention based access mechanism (for example theRACH (random access channel) mechanism described in TS 36.211 (seesection 5); finally, in some embodiments, both the SR and contentionbased resource request mechanisms are available to trigger thisbehaviour.

Various mechanisms have been described to trigger the start of SRStransmission in anticipation of data transmission. Various mechanismsare also provided to stop SRS transmission. The first example wasdescribed above and involved starting an inactivity timer upon receiptof an uplink grant; the SRS transmission stops upon expiry of theinactivity timer.

In another embodiment, the UE will simply stop the SRS transmission atthe end of the data transmission; in some embodiments at the earliestopportunity after data transmission has finished.

In some embodiments, SRS is transmitted during an original datatransmission and any retransmissions/HARQ processes that may follow. TheSRS transmission is transmitted from before data transmission untilcompletion of any retransmissions/HARQ processes.

In other embodiments, the SRS transmission is transmitted from beforetransmission of an original data transmission until completion of theoriginal data transmission after which SRS transmission is stopped. Inthe event that retransmissions are necessary, SRS transmission isrestarted in order to cover the retransmissions. As in the case fororiginal transmissions, this starts in anticipation of theretransmission and continues until completion of the retransmission.

Reference Signal Timing Alignment

In some embodiments, reference signal transmissions are made for twodifferent purposes:

-   -   a) to allow the network to assess the quality of the uplink        channel so that the network can determine an appropriate        adaptive modulation and encoding for uplink transmissions;    -   b) uplink timing alignment, as described previously.        The transmissions are the same in either case, but the network        may need them with differing timing constraints. For example,        the network may need the reference signal for uplink channel        quality assessment more frequently than for uplink timing        alignment. In some embodiments, rather than the UE making these        reference signal transmissions for timing alignment        independently of reference signal transmissions for uplink        channel assessment, the UE aligns the timing of these two        reference signal transmissions whenever possible and when the        timing is aligned, only a single reference signal transmission        is made.

Specifically, the network assigns the UE reference signal transmissionopportunities for timing alignment and reference signal transmissionopportunities for uplink channel quality assessment. For each referencesignal transmission opportunity, a single reference signal istransmitted if the current opportunity is aligned with one or both ofthe timing alignment or uplink channel quality assessment requirements.In some embodiments, this reference signal behaviour is predicated onreference signal transmission being enabled, for example using any ofthe mechanisms described in previous embodiments. A specific example ofthis method from the perspective of the UE will be described withreference to the flowchart of FIG. 7. The method begins at block 7-1with the UE receiving signalling that allocates reference signaltransmission opportunities for uplink timing alignment and referencesignal transmission opportunities for uplink channel quality assessment.Some of the reference signal transmission opportunities for uplinktiming alignment may coincide with reference signal transmissionopportunities for uplink channel quality assessment. The methodcontinues at block 7-2 with transmitting reference signal transmissionsfor uplink timing alignment in accordance with the signalling, and atblock 7-3 transmitting reference signal transmissions for uplink channelquality assessment in accordance with the signalling. In so doing,transmitting reference signal transmissions for uplink timing alignmentin accordance with the signalling and transmitting reference signaltransmissions for uplink channel quality assessment in accordance withthe signalling is achieved by transmitting a single reference signaltransmission for both uplink timing alignment and uplink channel qualityassessment for any reference signal transmission opportunities foruplink timing alignment that coincide with reference signal transmissionopportunities for uplink channel quality assessment.

An example of this method from the perspective of the network will bedescribed with reference to the flowchart of FIG. 8. The method beginsat block 8-1 with the network transmitting signalling that allocatesreference signal transmission opportunities for uplink timing alignmentand reference signal transmission opportunities for uplink channelquality assessment. The method continues at block 8-2 with receivingreference signal transmissions for uplink timing alignment in accordancewith the signalling, and at block 8-3 receiving reference signaltransmissions for uplink channel quality assessment in accordance withthe signalling. In so doing, receiving reference signal transmissionsfor uplink timing alignment in accordance with the signalling andreceiving reference signal transmissions for uplink channel qualityassessment in accordance with the signalling comprised receiving asingle reference signal transmission for both uplink timing alignmentand uplink channel quality assessment for any reference signaltransmission opportunities for uplink timing alignment that coincidewith reference signal transmission opportunities for uplink channelquality assessment.

In some embodiments, the network transmits signalling information thatcontains a definition of reference signal transmission opportunities tobe made available for one or both of channel quality assessment andtiming alignment. In addition, the signalling information includesinformation identifying a minimum period for transmission of thereference signal for channel quality assessment and/or a minimum periodfor transmission of the reference signal for timing alignment. The UEmakes reference signal transmissions in accordance with the definitionof reference signal transmission opportunities, and subject to theminimum period(s) such that whenever possible a single reference signalis sent for both channel quality assessment and timing alignment.

As a specific example, consider that a basic set of SRS transmissionopportunities may be defined with a periodicity of 10 ms; the SRS forchannel quality assessment may be required every 10 ms while the UE istransmitting; the SRS for timing alignment may be required every 30 msirrespective of whether the UE is transmitting. This information is usedby the UE to send a single SRS every 10 ms while the UE is transmittingin satisfaction of both requirements, and a single SRS every 30 ms whilethe UE is not transmitting.

In some embodiments, in order to carry out the above process, the UE 10comprises a processor capable of performing the above process. Forsimplicity, the different functions have been broken out into differentmodules. These modules may be implemented separately or together.Further, these modules may be implemented in hardware, software, or somecombination. Finally, these modules may reside in different portions ofthe UE memory. As illustrated in FIG. 9, the UE processor comprises areceive module 801, an uplink reference signal generation module 803,and a transmission module 807. The receive module 801 receivescommunications from the network. These may for example include a messageor messages configuring the on and off periods for the receiver, andconfiguring various resources for the receiver, such as the transmissionopportunities for the uplink reference signal, and uplink grants. Thetransmission module 807 makes uplink transmissions, including datatransmissions and uplink timing alignment signal transmissions. Thesecan be part of an integrated frame structure as described previouslywith reference to FIG. 3 by way of example. The uplink reference signalgeneration module 803 generates uplink reference signal transmissionsfor transmission by the transmission module 807 such that uplinkreference signal transmissions occur in anticipation of and during datatransmissions. This can occur using any of the methods describedearlier, for example.

FIG. 10 illustrates a wireless communications system including anembodiment of the UE 10. The UE 10 is operable for implementing aspectsof the disclosure, but the disclosure should not be limited to theseimplementations. Though illustrated as a mobile phone, the UE 10 maytake various forms including a wireless handset, a pager, a personaldigital assistant (PDA), a portable computer, a tablet computer, or alaptop computer. Many suitable devices combine some or all of thesefunctions. In some embodiments of the disclosure, the UE 10 is not ageneral purpose computing device like a portable, laptop or tabletcomputer, but rather is a special-purpose communications device such asa mobile phone, a wireless handset, a pager, a PDA, or atelecommunications device installed in a vehicle. In another embodiment,the UE 10 may be a portable, laptop or other computing device. The UE 10may support specialized activities such as gaming, inventory control,job control, and/or task management functions, and so on.

The UE 10 includes a display 402. The UE 10 also includes atouch-sensitive surface, a keyboard or other input keys generallyreferred as 404 for input by a user. The keyboard may be a full orreduced alphanumeric keyboard such as QWERTY, Dvorak, AZERTY, andsequential types, or a traditional numeric keypad with alphabet lettersassociated with a telephone keypad. The input keys may include a trackwheel, an exit or escape key, a trackball, and other navigational orfunctional keys, which may be inwardly depressed to provide furtherinput function. The UE 10 may present options for the user to select,controls for the user to actuate, and/or cursors or other indicators forthe user to direct.

The UE 10 may further accept data entry from the user, including numbersto dial or various parameter values for configuring the operation of theUE 10. The UE 10 may further execute one or more software or firmwareapplications in response to user commands. These applications mayconfigure the UE 10 to perform various customized functions in responseto user interaction. Additionally, the UE 10 may be programmed and/orconfigured over-the-air, for example from a wireless base station, awireless access point, or a peer UE 10.

Among the various applications executable by the UE 10 are a webbrowser, which enables the display 402 to show a web page. The web pagemay be obtained via wireless communications with a wireless networkaccess node, a cell tower, a peer UE 10, or any other wirelesscommunication network or system 400. The network 400 is coupled to awired network 408, such as the Internet. Via the wireless link and thewired network, the UE 10 has access to information on various servers,such as a server 410. The server 410 may provide content that may beshown on the display 402. Alternately, the UE 10 may access the network400 through a peer UE 10 acting as an intermediary, in a relay type orhop type of connection.

FIG. 11 shows a block diagram of the UE 10. While a variety of knowncomponents of UEs 10 are depicted, in an embodiment a subset of thelisted components and/or additional components not listed may beincluded in the UE 10. The UE 10 includes a digital signal processor(DSP) 502 and a memory 504. As shown, the UE 10 may further include anantenna and front end unit 506, a radio frequency (RF) transceiver 508,an analog baseband processing unit 510, a microphone 512, an earpiecespeaker 514, a headset port 516, an input/output interface 518, aremovable memory card 520, a universal serial bus (USB) port 522, ashort range wireless communication sub-system 524, an alert 526, akeypad 528, a liquid crystal display (LCD), which may include a touchsensitive surface 530, an LCD controller 532, a charge-coupled device(CCD) camera 534, a camera controller 536, and a global positioningsystem (GPS) sensor 538. In an embodiment, the UE 10 may include anotherkind of display that does not provide a touch sensitive screen. In anembodiment, the DSP 502 may communicate directly with the memory 504without passing through the input/output interface 518.

The DSP 502 or some other form of controller or central processing unitoperates to control the various components of the UE 10 in accordancewith embedded software or firmware stored in memory 504 or stored inmemory contained within the DSP 502 itself. In addition to the embeddedsoftware or firmware, the DSP 502 may execute other applications storedin the memory 504 or made available via information carrier media suchas portable data storage media like the removable memory card 520 or viawired or wireless network communications. The application software maycomprise a compiled set of machine-readable instructions that configurethe DSP 502 to provide the desired functionality, or the applicationsoftware may be high-level software instructions to be processed by aninterpreter or compiler to indirectly configure the DSP 502.

The antenna and front end unit 506 may be provided to convert betweenwireless signals and electrical signals, enabling the UE 10 to send andreceive information from a cellular network or some other availablewireless communications network or from a peer UE 10. In an embodiment,the antenna and front end unit 506 may include multiple antennas tosupport beam forming and/or multiple input multiple output (MIMO)operations. As is known to those skilled in the art, MIMO operations mayprovide spatial diversity which can be used to overcome difficultchannel conditions and/or increase channel throughput. The antenna andfront end unit 506 may include antenna tuning and/or impedance matchingcomponents, RF power amplifiers, and/or low noise amplifiers.

The RF transceiver 508 provides frequency shifting, converting receivedRF signals to baseband and converting baseband transmit signals to RF.In some descriptions a radio transceiver or RF transceiver may beunderstood to include other signal processing functionality such asmodulation/demodulation, coding/decoding, interleaving/de-interleaving,spreading/de-spreading, inverse fast Fourier transforming (IFFT)/fastFourier transforming (FFT), cyclic prefix appending/removal, and othersignal processing functions. For the purposes of clarity, thedescription here separates the description of this signal processingfrom the RF and/or radio stage and conceptually allocates that signalprocessing to the analog baseband processing unit 510 and/or the DSP 502or other central processing unit. In some embodiments, the RFTransceiver 508, portions of the Antenna and Front End 506, and theanalog baseband processing unit 510 may be combined in one or moreprocessing units and/or application specific integrated circuits(ASICs).

The analog baseband processing unit 510 may provide various analogprocessing of inputs and outputs, for example analog processing ofinputs from the microphone 512 and the headset 516 and outputs to theearpiece 514 and the headset 516. To that end, the analog basebandprocessing unit 510 may have ports for connecting to the built-inmicrophone 512 and the earpiece speaker 514 that enable the UE 10 to beused as a cell phone. The analog baseband processing unit 510 mayfurther include a port for connecting to a headset or other hands-freemicrophone and speaker configuration. The analog baseband processingunit 510 may provide digital-to-analog conversion in one signaldirection and analog-to-digital conversion in the opposing signaldirection. In some embodiments, at least some of the functionality ofthe analog baseband processing unit 510 may be provided by digitalprocessing components, for example by the DSP 502 or by other centralprocessing units.

The DSP 502 may perform modulation/demodulation, coding/decoding,interleaving/de-interleaving, spreading/de-spreading, inverse fastFourier transforming (IFFT)/fast Fourier transforming (FFT), cyclicprefix appending/removal, and other signal processing functionsassociated with wireless communications. In an embodiment, for examplein a code division multiple access (CDMA) technology application, for atransmitter function the DSP 502 may perform modulation, coding,interleaving, and spreading, and for a receiver function the DSP 502 mayperform de-spreading, de-interleaving, decoding, and demodulation. Inanother embodiment, for example in an orthogonal frequency divisionmultiplex access (OFDMA) technology application, for the transmitterfunction the DSP 502 may perform modulation, coding, interleaving,inverse fast Fourier transforming, and cyclic prefix appending, and fora receiver function the DSP 502 may perform cyclic prefix removal, fastFourier transforming, de-interleaving, decoding, and demodulation. Inother wireless technology applications, yet other signal processingfunctions and combinations of signal processing functions may beperformed by the DSP 502.

The DSP 502 may communicate with a wireless network via the analogbaseband processing unit 510. In some embodiments, the communication mayprovide Internet connectivity, enabling a user to gain access to contenton the Internet and to send and receive e-mail or text messages. Theinput/output interface 518 interconnects the DSP 502 and variousmemories and interfaces. The memory 504 and the removable memory card520 may provide software and data to configure the operation of the DSP502. Among the interfaces may be the USB interface 522 and the shortrange wireless communication sub-system 524. The USB interface 522 maybe used to charge the UE 10 and may also enable the UE 10 to function asa peripheral device to exchange information with a personal computer orother computer system. The short range wireless communication sub-system524 may include an infrared port, a Bluetooth interface, an IEEE 802.11compliant wireless interface, or any other short range wirelesscommunication sub-system, which may enable the UE 10 to communicatewirelessly with other nearby mobile devices and/or wireless basestations.

The input/output interface 518 may further connect the DSP 502 to thealert 526 that, when triggered, causes the UE 10 to provide a notice tothe user, for example, by ringing, playing a melody, or vibrating. Thealert 526 may serve as a mechanism for alerting the user to any ofvarious events such as an incoming call, a new text message, and anappointment reminder by silently vibrating, or by playing a specificpre-assigned melody for a particular caller.

The keypad 528 couples to the DSP 502 via the interface 518 to provideone mechanism for the user to make selections, enter information, andotherwise provide input to the UE 10. The keyboard 528 may be a full orreduced alphanumeric keyboard such as QWERTY, Dvorak, AZERTY andsequential types, or a traditional numeric keypad with alphabet lettersassociated with a telephone keypad. The input keys may include a trackwheel, an exit or escape key, a trackball, and other navigational orfunctional keys, which may be inwardly depressed to provide furtherinput function. Another input mechanism may be the LCD 530, which mayinclude touch screen capability and also display text and/or graphics tothe user. The LCD controller 532 couples the DSP 502 to the LCD 530.

The CCD camera 534, if equipped, enables the UE 10 to take digitalpictures. The DSP 502 communicates with the CCD camera 534 via thecamera controller 536. In another embodiment, a camera operatingaccording to a technology other than Charge Coupled Device cameras maybe employed. The GPS sensor 538 is coupled to the DSP 502 to decodeglobal positioning system signals, thereby enabling the UE 10 todetermine its position. Various other peripherals may also be includedto provide additional functions, e.g., radio and television reception.

FIG. 12 illustrates a software environment 602 that may be implementedby the DSP 502. The DSP 502 executes operating system drivers 604 thatprovide a platform from which the rest of the software operates. Theoperating system drivers 604 provide drivers for the wireless devicehardware with standardized interfaces that are accessible to applicationsoftware. The operating system drivers 604 include applicationmanagement services (“AMS”) 606 that transfer control betweenapplications running on the UE 10. Also shown in FIG. 12 are a webbrowser application 608, a media player application 610, and Javaapplets 612. The web browser application 608 configures the UE 10 tooperate as a web browser, allowing a user to enter information intoforms and select links to retrieve and view web pages. The media playerapplication 610 configures the UE 10 to retrieve and play audio oraudiovisual media. The Java applets 612 configure the UE 10 to providegames, utilities, and other functionality. A component 614 might providefunctionality related to the present disclosure.

The UEs 10, ENBs 20, and central control 110 of FIG. 1 and othercomponents that might be associated with the cells 102 may include anygeneral-purpose computer with sufficient processing power, memoryresources, and network throughput capability to handle the necessaryworkload placed upon it. FIG. 13 illustrates a typical, general-purposecomputer system 700 that may be suitable for implementing one or moreembodiments disclosed herein. The computer system 700 includes aprocessor 720 (which may be referred to as a central processor unit orCPU) that is in communication with memory devices including secondarystorage 750, read only memory (ROM) 740, random access memory (RAM) 730,input/output (I/O) devices 700, and network connectivity devices 760.The processor may be implemented as one or more CPU chips.

The secondary storage 750 is typically comprised of one or more diskdrives or tape drives and is used for non-volatile storage of data andas an over-flow data storage device if RAM 730 is not large enough tohold all working data. Secondary storage 750 may be used to storeprograms which are loaded into RAM 730 when such programs are selectedfor execution. The ROM 740 is used to store instructions and perhapsdata which are read during program execution. ROM 740 is a non-volatilememory device which typically has a small memory capacity relative tothe larger memory capacity of secondary storage. The RAM 730 is used tostore volatile data and perhaps to store instructions. Access to bothROM 740 and RAM 730 is typically faster than to secondary storage 750.

I/O devices 700 may include printers, video monitors, liquid crystaldisplays (LCDs), touch screen displays, keyboards, keypads, switches,dials, mice, track balls, voice recognizers, card readers, paper tapereaders, or other well-known input devices.

The network connectivity devices 760 may take the form of modems, modembanks, Ethernet cards, universal serial bus (USB) interface cards,serial interfaces, token ring cards, fiber distributed data interface(FDDI) cards, wireless local area network (WLAN) cards, radiotransceiver cards such as code division multiple access (CDMA) and/orglobal system for mobile communications (GSM) radio transceiver cards,and other well-known network devices. These network connectivity 760devices may enable the processor 720 to communicate with an Internet orone or more intranets. With such a network connection, it iscontemplated that the processor 720 might receive information from thenetwork, or might output information to the network in the course ofperforming the above-described method steps. Such information, which isoften represented as a sequence of instructions to be executed usingprocessor 720, may be received from and outputted to the network, forexample, in the form of a computer data signal embodied in a carrierwave.

Such information, which may include data or instructions to be executedusing processor 720 for example, may be received from and outputted tothe network, for example, in the form of a computer data baseband signalor signal embodied in a carrier wave. The baseband signal or signalembodied in the carrier wave generated by the network connectivity 760devices may propagate in or on the surface of electrical conductors, incoaxial cables, in waveguides, in optical media, for example opticalfiber, or in the air or free space. The information contained in thebaseband signal or signal embedded in the carrier wave may be orderedaccording to different sequences, as may be desirable for eitherprocessing or generating the information or transmitting or receivingthe information. The baseband signal or signal embedded in the carrierwave, or other types of signals currently used or hereafter developed,referred to herein as the transmission medium, may be generatedaccording to several methods well known to one skilled in the art.

The processor 720 executes instructions, codes, computer programs,scripts which it accesses from hard disk, floppy disk, optical disk(these various disk-based systems may all be considered secondarystorage 750), ROM 740, RAM 730, or the network connectivity devices 760.While only one processor 720 is shown, multiple processors may bepresent. Thus, while instructions may be discussed as executed by aprocessor, the instructions may be executed simultaneously, serially, orotherwise executed by one or multiple processors.

While several embodiments have been provided in the present disclosure,it should be understood that the disclosed systems and methods may beembodied in many other specific forms without departing from the spiritor scope of the present disclosure. The present examples are to beconsidered as illustrative and not restrictive, and the intention is notto be limited to the details given herein. For example, the variouselements or components may be combined or integrated in another systemor certain features may be omitted, or not implemented.

Also, techniques, systems, subsystems and methods described andillustrated in the various embodiments as discrete or separate may becombined or integrated with other systems, modules, techniques, ormethods without departing from the scope of the present disclosure.Other items shown or discussed as coupled or directly coupled orcommunicating with each other may be indirectly coupled or communicatingthrough some interface, device, or intermediate component, whetherelectrically, mechanically, or otherwise. Other examples of changes,substitutions, and alterations are ascertainable by one skilled in theart and could be made without departing from the spirit and scopedisclosed herein.

What is claimed is:
 1. A non-transitory computer readable medium havingstored therein computer executable instructions for implementing amethod in a user equipment, the method comprising: controlling areceiver to use discontinuous reception associated with configured onperiods and off periods; maintaining a configuration of a set ofsounding reference signal transmission resources; transmitting a requestfor an uplink transmission resource during one of the off periods; andtransmitting a sounding reference signal transmission, using at leastone of the set of sounding reference signal transmission resourcesassociated with the configuration, responsive to transmitting therequest for the uplink transmission resource.
 2. The computer readablemedium of claim 1, wherein the method further comprises: receivingsignalling to configure the user equipment to be able to transmit,irrespective of the on and off periods of the receiver, the request forthe uplink transmission resource.
 3. The computer readable medium ofclaim 1, wherein transmitting the request for the uplink transmissionresource comprises transmitting the request using an assigned schedulingrequest channel.
 4. The computer readable medium of claim 1, whereintransmitting the request for the uplink transmission resource comprisestransmitting a request for uplink transmission using a previouslyassigned semi-persistent resource.
 5. The computer readable medium ofclaim 1, wherein transmitting the request for the uplink transmissionresource comprises transmitting a request for uplink transmission usinga contention based access channel.
 6. The computer readable medium ofclaim 1, wherein said transmitting the sounding reference signaltransmission occurs as a result of said transmitting the request for theuplink transmission resource.
 7. The computer readable medium of claim1, wherein the set of sounding reference signal transmissions repeatperiodically.
 8. The computer readable medium of claim 1, wherein themethod further comprises starting an inactivity timer upon reception ofan uplink transmission resource grant.
 9. The computer readable mediumof claim 8, wherein the method further comprises transmitting a soundingreference signal transmission in at least one of the set of soundingreference signal transmission resources until the inactivity timerexpires.
 10. A non-transitory computer readable medium having storedtherein computer executable instructions for implementing a method in auser equipment, the method comprising: controlling a receiver of theuser equipment to use discontinuous reception associated with configuredon periods and off periods, wherein the user equipment is a lone termevolution user equipment; maintaining a sounding reference signalconfiguration; transmitting a request for an uplink transmissionresource during one of the off periods; and transmitting a soundingreference signal transmission, using at least one sounding referencesignal transmission resource associated with the configuration,responsive to transmitting the request for the uplink transmissionresource.
 11. The computer readable medium of claim 10, wherein themethod further comprises: receiving signalling to configure the userequipment to be able to transmit, irrespective of the on and off periodsof the receiver, the request for the uplink transmission resource. 12.The computer readable medium of claim 10, wherein transmitting therequest for the uplink transmission resource comprises transmitting therequest using an assigned scheduling request channel.
 13. The computerreadable medium of claim 10, wherein transmitting the request for theuplink transmission resource comprises transmitting a request for uplinktransmission using a previously assigned semi-persistent resource. 14.The computer readable medium of claim 10, wherein transmitting therequest for the uplink transmission resource comprises transmitting arequest for uplink transmission using a contention based access channel.15. The computer readable medium of claim 10, wherein said transmittingthe sounding reference signal transmission occurs as a result of saidtransmitting the request for the uplink transmission resource.
 16. Thecomputer readable medium of claim 10, wherein the sounding referencesignal transmission repeats periodically.
 17. The computer readablemedium of claim 10, wherein the method further comprises starting aninactivity timer upon reception of an uplink transmission resourcegrant.
 18. The computer readable medium of claim 17, wherein the methodfurther comprises transmitting a sounding reference signal transmissionin the at least one sounding reference signal transmission resourceuntil the inactivity timer expires.